Negley entered the Union Army as a brigadier general on April 19, 1861. He organized and equipped volunteers from the area of Pittsburg, PA. Until February 1862, when Negley was promoted and transferred to the Army of the Ohio. He served in Nashville, building a fort during the Union occupation to defend the city against potential reoccupation by Confederate forces. In June 1862, Negley led a small force to capture Chattanooga. In December 1862, he served as a division commander at the battles of Stone's River. Thus, Negley was promoted to major general for his service. He joined General Sherman in October 1861 and was promoted to major general.
